This laboratory has developed a radioimmunoassay which permits detection of IgE antibodies to TDI in persons with clinical hypersensitivity to toluene diisocyanate (TDI). Success of the assay depends on use of a p-toluene (mono) isocyanate-human serum albumin conjugate as test antigen to detect antibodies to TDI. Since publication of the availability of the assay, requests have been received from major TDI production and utilization facilities (national and international) to have their workers participate in a large scale serologic screening program for TDI antibodies. Coincident with the screening program, efforts will be directed toward development of other TDI test antigens which may likely offer increased sensitivity and/or specificity in detecting antibodies to TDI. For these studies, protein conjugates of o-tolyl (mono) isocyanate and m-tolyl (mono) isocyanate will each be evaluated as will TDI-conjugates. Radioassays for IgE antibodies to other diisocyanates of industrial importance (HDI, MDI, IPDI, NDI, and hydrogenated MDI) will also be developed. Test antigens for initial studies will be prepared using monoisocyanate analogues of corresponding diisocyanates. Serologic assays for IgE antibodies to low molecular weight industrial chemicals other than isocyanates (for example, formaldehyde) will be developed by application of the guinea pig animal model of respiratory hypersensitivity previously developed by this laboratory. From such animal studies, information will be obtained regarding both the respiratory sensitizing potency of the chemicals and the most effective antigen for detecting specific antibodies. Sera from workers sensitized to these chemicals will be obtained from the industrial screening program currently underway in this laboratory.